Photographic emulsions, developers, and processes of photography



than May 29, 1945 PHOTOGRAPHIC EMULSIONS, DEVELOPERS, AND PROCESSES OFPHOTOGRAPHY Cyril D. Wilson,- Metuchen, N. J., assignor to E. I. du Pontde Nemours & Company, Wilmington, Del., a corporation of Delaware NoDrawing. Application February 4, 1943,

' Serial No. 474,688

I rclaims. (c1. 95-6) This invention relates to color photography. Moreparticularly it relates to new chemical compounds and to photographicemulsions and developer solutions containing the novel compounds ascolor formers. Still more particularly it relates to aforesaidcompositions containing colorforming compounds which contain at leastone azole radical. The invention also relates to dyes produced bythe'use of such color formers and to methods forpmducing dye imagesutilizing the novel color formers hereof.

,This invention has for'an object the provision of a new class of colorformers which may be used in developer solutions and emulsions. Afurther object is to provide new color formers which can be economicallymade from readily available chemical compounds. A still further objectis the production of developer solutions and. emulsion layers containingcolor formers of good tinctorial strength and color. A still furtherobject is the .production of color-formers which do not afiect thesensitivity of photographic emulsions. Still other objects will'beapparent from the follow-' ing specification.

The above and other objects are accomplished by the preparation and usein photo-emulsions and processing solutions, especially developingsolutions, of methylene bis azoles which are characterized in that twoazole radicals are joined by a methylene radical at the median carbonatom. The compounds have the general formula:

wherein A and A constitute the atoms necessary to form an azole ring ofthe same or different t p e. g., an oxazole, thiazole, selenazole ortellurazole ring. The azole nuclei may be monocyclic or polycyclic. Thatis, they may contain carbocyclic ring systems fused onto the ringcontaining the hetero atoms.

In a more preferred embodiment of the invention the compounds containtwo ring systems in eachazole radical and may be represented by theBcneral formula: (in x '/x' Y C-CHr-C Y wherein x and X may be the sameordifierent and represent a chalcogen (defined in U. S. P. 2,323,503 andthe Jour. Am. Chem. Soc., volume 83, page 889,) or an atomfrom theoxygen family such as oxygen, sulfur, selenium and tellurium atoms, andY andY' may be the same or different and represent hydrogen, aminoalkylradicals 01' l to 20 carbon atoms, e. g. ethyl, methyl, dodecyl, etc.,cycloalkyl, e. g. cyclohexyl, methylcyclohexyl, ethylcyclohexyl,menthyl, aryl, e. g. phenyl, naphthyl, chlorphenyl, etc., aralkyl, e. g.benzyl, methylbenzyl, menaphthyl, etc., carboxyllc acyl, includingaliphatic acyl, e. g. acetyl, butyryi. lauroyl, stearoyl, caproyl, etc.,heterocyclicacyl, e. g. thienoyl nlcotinoyl, isonicotinoyl, etc., cyclicacyl, e. g. benzoyl naphthoyl, etc., preferabyl containing at least '6carbon atoms. The benzene nuclei of the above furthermore may have oneor more water-lnsolubilizing groups substituted thereon, e. g., alkyl,alkoxy, e. g. methoxy, ethoxy, etc., halogen, e. g. chlorine, bIO-t mineand nitro groups or, if desired, solubilizing groups such as hydroxylsulfonic and carboxylic acid and their salts.

In a still'more preferred embodiment of the inventionthe compoundscontain two ring systems in each azole radical which are selected fromthe group consisting of thiazole and oxazole radicals. Such preferredcompounds have the structure of Formula 2 but X and X are limited tooxygen or sulfur atoms. These compounds are more easily prepared, thestarting materials are more readily available and the resulting dyeshave better color values and stability than the remaining membersfalling within the generic formula.

In preparing the novel color formers hereof a malonic acid ester isreacted with two mols of an amino compound containing in an orthoposition' to the NH: group an OH, SH, -SeH or TeH group or one molof'each of two compounds of aforesaid type. Thus, symmetrical andunsymmetrical dyes may be prepared. The preparation of the former may beexemplified by the following equation, wherein ortho amino thiophenol isreacted with diethyl malonate:

' min l I sin poi 0a Hi5 The reaction may be accomplished by dissolvingor suspending the two reactants in an inert organic solvent, preferablya volatile hydrocarbon solvent such as xylene, and heating the mixtureunder reflux 'for several hours until ring closure obtains. The mixtureis cooled, filtered and the product recrystallized or distilled,depending upon One mol of the diethyl ester of malonic acid I dissolvedin xylene and two mols of o-amino thiophenol is added to the boilingmixture. The mixture is refluxed for 2 to 3 hours at a temperature ofabout 140 C., cooled, filtered and the resuiting product purified.

Example II One mol of the dlethyl ester of malonic acid is dissolved inxylene and two mols of o-aminophenol are added with stirring to theboiling mixture. The reaction mixture-is heated under reflux for severalhours and-then at a temperature of 200" C. for several hours. Thesolution is chilled and the crystals recrystallized.

In place of the specific amino compounds of the above examples may besubstituted various other aromatic compounds containing an amino groupand a reactive hydrogen atom attached to an atom from the oxygen familyof elements. Thus, o-amino bromophenol, o-amino chlorophenol, o-aminobromo-thiophenol, o-amino nitrophenol, o-amino selenophenol,o-amino-telluropl'zenol, etc. may be substituted in similar amounts.

when an unsymmetrical compound is desired a mixture of equal parts ofthe amino phenols, for instance, a mol of o-aminophenol and a mol ofo-aminothiophenol are reacted with an equivalent amount of the malonicacid ester. Another method of preparing the unsymmetrical compoundsinvolves the stepwise reaction of the components. Thus, one mol of anamino phenol is reacted with one mol of the malonic ester and theresulting product reacted with one mol of a diii'erent aminophenol, e.8. an aminothiophenol or a methoxylaminophenol.

Various types of malonic acid esters may be substituted for the diethylester above described.

- Thus, the dimethyl, diisopropyl, dibutyl, diben- The above exampleswhich are all drawn to the preparation of the his methyleneil-azolesineludethe preparation of a number of new chemical compounds.Thus, the unsymmetrical compounds and the nuclear substitutedsymmetrical compounds are believed to be new and have'considerableutility. The new compounds are claimed in United States Patent2,323,503.

The compounds or mixtures may be introduced into photographic emulsionlayers or developer solutions as previously described and dyes producedtherefrom by some suitable treatment such as exposure and developmentwith a color forming developer, or treatment with a diazo compound toyield an over-all dye followed by localized bleaching of the dye in theimage areas. In the case of emulsions the color-tormers are dissolved inalkali or carbonate solutions. Small amounts of organic solvents, e. s.alcohol or acetone may be used.

The remaining examples are directed to the us of the compounds ormixtures of the same in various photographic compositions and toprocesses of developing dyed images utilizing such compounds.

Example II! Tome. ccs. of 2% by weight aqueous gelatin solution is addeda solution consisting of 8 cos. of ethyl alcohol and 1 gram of thecompound havinga melting point of 92.3' C. and being of the formula:

1, c--on -o D I s s I The total weight of the combined solution is thenbrought to about 150 grams with water and then the mixture is added tograms of a gelatinosilver halide emulsion and mixed thoroughly. Theresulting emulsion may then be coated upon a suitable support such aspaper, glass or a cel- To 100 cos. of 2% by ,weight aqueous gelatinsolution is addeda solution consisting of 8 cos. of ethyl alcohol and 1gram of the compound having the formula:

which decomposes at about 223 C. The total weight of the combinedsolution is then brought to about grams with water and then the mixtureis added to 100 grams of a gelatino-silver halide emulsion and mixedthoroughly. The resulting emulsion may then be coated upon a suitablephotographic support after the manner described in Example HI. Afterexposure the photographic element isdeveloped in an alkaline solutioncontaining diethyl-p phenylene diamine, whereupon a yellow-orange dye ofgood tinctoriaist'rensth isformed. v

Similar results were obtained with-methylene bis-nitrobenzoxazole havinga melting point above 310 C, which i'orms an orange dye and thecorresponding amino compound which gives a brick red dye. This lattercompound also acts as a developer.

Example V To 100 cos. of 2% by weight aqueous gelatin solution is addeda solution consisting of 8 cos. of ethyl alcohol and 1.5 grams of thecompound having the formula:

which has a melting point of about 88 to 89 C., together'with a 20%aqueous caustic soda solution in an amount equal to 2 mols of alkali foreach mol of the compound. The total weight of the combined solution isthen brought to about 150 grams with water and then the mixture is.

Example VI To 100 cos. of 2% by weight aqueous gelatin solutionconsisting of 8 cos. of ethyl alcohol and 1.5 grams of the compoundhaving a melting point of 115 C. and being'of the formula:

together with a 20% aqueous caustic soda solution in an amount equal to2 mols of alkali for each moi of the compound. The total weight of thecombined solution is then brought to about 150 grams with water and thenthe mixture is added to 100 grams of a gelatino-silver halide emulsionand mixed thoroughly. The resulting emulsion may then be coated upon asuitable photographic support after the manner described in Example III.After exposure the photographic element is developed in an alkalinesolution containing dimethyl-p-phenylene diamine, whereupon an orangedye light in color and of good tinctorial strength is formed.

'2 Example V II To 100 cos. of a developer having the followingcomposition:

. 3 silver chloro-broinide, silver bromide-iodide, etc., emulsions.They'may be used with latent images or reversed or bleached images andform dyes in situ with metallic silver. Upon removal of the silvertransparent dye images are left.

The dye intermediates used in this invention are not limited in theirutility to any one process are added from 0.1 to 1.0 grams of methylenebis- -benzothiazole (compound of Example I) dissolved in a few cos. ofethyl alcohol. An exposed photographic element containing exposed silversalts is then developed in aforedescribed solution.

The color formers hereof may be used with various types of emulsions andare especially useful in the development of gelatlno silver halide ofcolor photography. They are suitable for dye coupling development withp-phehylenediamine derivatives, and by suitably controlling themolecular weights of the products, they may be used in the colordeveloper or in the photographic emulsion. Furthermore, the dyecomponents of this invention coupl with diazo compounds, e. g.tetrazotized diansidine, so that they are therefore suitable fortransforming into'azo dyes, followed or not by difierential bleaching inthepresence of silver images as is known in the art.

They may be used in multilayer or single layer films.

The preferred developing agents in the process of dye couplingdevelopment are derivativesof p-phenylenediamine andparticularly theasymmetric dialkyl p-phenylenediamines, e. g. paminodimethylaniline,p-aminodiethylaniline, paminodibutylaniline, etc. Other developingagents which may be used include p-phenylenediamine itself,p-methylaminoaniline, p-ethylaminoaniline, p-aminophenol,N,N-diethyl-,o-

phenylenediamino, chloro-p-phenylenediamine, 1,2,5-toluylenediamine,2-amino-5-diethylaminotoluene, N-p-aminophenylpiperidine, N-methyl-N-hydroxy-ethyl-p-phenylene diamine, N-butyl-'N-hydroxyethyl-p-phenylenediamine, beta-gam ma dihydroxypropyl pphenylenediamine, 2

amino-5-(N-beta-hydroxy-ethyl-N-butyl) aminotoluene and itsdihydrochloride, etc. These aromatic amino-developing agents may be usedin the form of their salts, which may be either inorganic or organic.The salts are in general more stable than the free bases. As examples ofsuitable salts mention is made of the hydrochloride, sulfates, acetates,etc.

- This application is a continuation-in-part of my copending applicationSer'. No. 303,872, filed November 10, 1939, now U. S. P. 2,323,503.

As many apparently'widely diflerent embodiments of this invention maybemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodiments hereofexcept as defined by the appended claims.

, wherein X and X represent a chalcogen and Y and Y are members takenfrom the class consisting of hydrogen, alkyl, cycloalkyl,aryl, aralkyl,alkoxy, halogen, nitro, and amino radicals.

emulsions such as silver chloride, silver bromide, 76 3. A photographicelement bearing an emul" m layer containing a light sensitive silverhalide and a compound of the general formula:

wherein x and 2' represent a chaicogen and Y and Y are members takenfrom the class consistlng of hydrogen, alkyl, cycloalhvl, aryl, aralkyl,alkoxy. halogen. nltro and amino radicals.

4. A photographic developer solution containin: an aromatic primaryamino developing agent and a methylene bis- -azole, wherein each azolenucleicontalns a single hetero nitrogen atom having a double bondattached thereto and a chalcogen and is ioinedothrough the mu carbonatom to the methylene group.

5. A photographic developer solution containin: an aromatic primaryamino developing agent and a compound of the general formula:

whe'reinAandA' constitutetheatomsnecessarytoiormamononit'rogenaaoleringorsameor different type.

8. A photographic developer solution containin: an aromatic primaryamino developing agent and a compound of the general formula:

o-cnr-c Y C'YRIL D. WILSON.

